By DAVID W. DUNLAP
Published: April 9, 2008
One World Trade Center has not yet emerged from below ground, but its facade has already survived earthquakes, hurricanes and an explosion that shook the earth a quarter-mile away.

In recent months, two full-size mock-ups of a few floors of the glass and aluminum facade have been built and tested. One is outside Los Angeles, in Ontario, Calif. The other was at a site in central New Mexico that can be reached only over dirt roads in four-wheel-drive vehicles.

At 1,368 feet, with 23 acres of glass-clad surface area, 1 World Trade Center will be subject to tremendous natural forces. The building, also known as the Freedom Tower (at a symbolic 1,776 feet, when its mast is counted), will be the tallest in New York City and as the skyscraping phoenix on the site of ground zero, it may be the target of terrorist attacks, too.

The Port Authority of New York and New Jersey, which is building 1 World Trade Center, and Skidmore, Owings & Merrill, which designed it, said both mock-ups performed well. The facade, called a curtain wall, is being made by Benson Industries of Portland, Ore. The engineering firm Weidlinger Associates is the consultant in blast-resistant design.

“Physical testing is a confirmation that curtain-wall contractors are in fact meeting performance requirements,” said Carl Galioto, a Skidmore partner. “Full fabrication of the curtain wall cannot begin until the mock-up specimen passes these tests.”

Almost invisible to passers-by, the foundations of 1 World Trade Center are rising every day toward street level.

The first mock-up was subjected to a blast test in Socorro, N.M., at the Energetic Materials Research and Testing Center, a division of the New Mexico Institute of Mining and Technology. Because details might arm a prospective attacker — providing information like how much force the curtain wall is designed to withstand — officials would say almost nothing about the test of this mock-up.

“The simple answer is, yes, it passed,” said John McCullough, the project executive for the Port Authority.

He was more forthcoming about the tests last month at Construction Consulting Laboratory West in California. There, a $537,000 mock-up was built to represent a corner of three typical tower floors, with laminated glass panes one and a half inches thick. The largest are 5 feet by 13 feet and weigh half a ton. An enclosed steel chamber was constructed behind the glass and aluminum cladding.

The goal was to find out how much air and water leakage could be expected under storm conditions that could be expected at least once in 50 years.

Water jets simulating winds of 74 miles per hour were sprayed at the facade. During the 15-minute test cycle, each square foot of glass was hit with more than a gallon of water.

In another test, a dismounted airplane propeller was switched on to simulate even-stronger and more-scattered winds. “It’s pretty colorful,” said Mr. Galioto, who witnessed the test. “It’s very noisy. Water is blowing in every direction and smoke is blowing from the engine.”

Air infiltration is measured by gauges. Water infiltration is measured by witnesses who are inside the chamber.

“Water is coming into the face of the curtain wall with such intensity that you can’t see,” said Bruce Fox, the deputy project executive for the Port Authority. “Then you’re looking into and opening up all the different pieces to see if there’s any evidence of leakage.” There was none.

Hydraulic jacks were used to simulate the different horizontal sway of various floors, both fully occupied and empty. The surface was also chilled to 10 degrees (refrigerated piping was applied to the glass) and baked at 100 degrees (by heat lamps).

Gusts up to 167 m.p.h. were simulated by using pumps to pull air out of the chamber, creating a condition in which the external air pressure was far greater than the internal pressure. The process was reversed, too, by pumping air into the chamber, simulating conditions on the side of the tower away from the wind.

An earthquake was simulated by jacks pulling the mock-up in different directions. Finally, a much stronger earthquake was simulated. At this point, the designers no longer expected the mock-up to remain airtight and watertight. But the criteria required that no glass could crack and no panes could be dislodged.

Mr. McCullough of the Port Authority said the mock-up met all the performance criteria.

And Mr. Fox marveled: “Sometimes on these tests, you have to do forensics and do corrections. Here, we had no failure at all.”

yeah the test facade looks good they should take it and use it on the real building. It's really good to see them put the tower to the test. But what about some of the older building in the city. Next time the might want to take our pride and go after the empire state building. But I don't think anything like 9/11 will happing again at less not in my life time.

A new version of the observation deck atop the World Trade Center that beguiled lovers and tourists - and even jaded New Yorkers - will soon rise at the Freedom Tower.

The Port Authority said Wednesday it is seeking a world-class operator to design, build and manage the indoor deck on the 102nd floor of the 1,776-foot icon at Ground Zero.

Boasting eye-popping, heart-stopping, 360-degree panoramic views that stretch forever - or at least 50 miles on a clear day - the deck will be perched 1,300 feet above West St. on the tower's highest occupied floor.

The rebirth of New York's signature rooftop was announced as another key element of post-9/11 rebuilding fell into place: The Sept. 11 Memorial & Museum said yesterday it had reached its goal of raising $350million in funds from private donors.

A record $10 million corporate gift from Cantor Fitzgerald, the financial services firm that lost 658 workers in the terror attacks, put the museum over the top. It's now flush with donations from 60,000 people in all 50 states and 31 nations.

"We reached our fund-raising goal because of support from people across the country and around the world," said Mayor Bloomberg, who doubles as museum chairman.

The project, which will cost a total of $610 million, will also receive state and federal grants.

The twin announcements provided fresh momentum for a rebuilding drive that has been haunted by years of delays, funding shortfalls and interagency squabbling. Officials now say the museum will open in 2011 and the Freedom Tower in 2012.

Occupying 18,000 square feet, the tower'snew observation deck will be smaller than the 44,000-square-foot original on the 107th floor of the south tower of the World Trade Center. Along with an open-air deck on the 110th floor, it drew 2 million visitors a year.

"It was a can't-miss stop," said PA Chairman Anthony Coscia. "We intend to recreate the same experience for future generations."

The bistate agency will issue a request for qualified developers early next month.

By June next year, an operator will be tapped, and the deck will open to the public three years later.

And it will be nearly the same view as till 911 except those new towers beeing build in Manhattan and the 30m that it will be located more to the north! I am wondering if the announced rebirth of the former windows on the world restaurant will be located in the WTC2 towers top floors. Mhhh if so it will be strange to have the ob-deck in 1WTC and the restaurant in 2WTC, before 911 it was the other way around.

The Sept. 11 Memorial & Museum said yesterday it had reached its goal of raising $350million in funds from private donors. The project, which will cost a total of $610 million, will also receive state and federal grants.

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Spending $610m (more than the cost of every WWII and holocaust memorial on the planet) won't bring back those who died 9/11, though it could be used to beef up security so future attacks will have a lower probability of happening.

For a fraction of the cost, a memorial could have been put on the top of WTC 1 nearer the heavens. Instead, a gigantic tribute to victimization and self-pity has been put underground, closer to hell, with a design that allows anyone with a good throwing arm to use it as a wastebasket.

Spending $610m (more than the cost of every WWII and holocaust memorial on the planet) won't bring back those who died 9/11, though it could be used to beef up security so future attacks will have a lower probability of happening.

For a fraction of the cost, a memorial could have been put on the top of WTC 1 nearer the heavens. Instead, a gigantic tribute to victimization and self-pity has been put underground, closer to hell, with a design that allows anyone with a good throwing arm to use it as a wastebasket.